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Gemini 3.5 Flash vs GLM-5.1

Head-to-head comparison across 3benchmark categories. Overall scores shown here use BenchLM's provisional ranking lane.

Gemini 3.5 Flash

88

VS

GLM-5.1

83

2 categoriesvs1 categories

Verified leaderboard positions: Gemini 3.5 Flash #7 · GLM-5.1 #23

Pick Gemini 3.5 Flash if you want the stronger benchmark profile. GLM-5.1 only becomes the better choice if coding is the priority or you want the cheaper token bill.

Category Radar

Head-to-Head by Category

Category Breakdown

Agentic

Gemini 3.5 Flash
77.2vs65.3

+11.9 difference

Coding

GLM-5.1
54.5vs60.9

+6.4 difference

Knowledge

Gemini 3.5 Flash
58vs52.3

+5.7 difference

Operational Comparison

Gemini 3.5 Flash

GLM-5.1

Price (per 1M tokens)

$1.5 / $9

$1.4 / $4.4

Speed

284.2 t/s

N/A

Latency (TTFT)

18.55s

N/A

Context Window

1M

203K

Quick Verdict

Pick Gemini 3.5 Flash if you want the stronger benchmark profile. GLM-5.1 only becomes the better choice if coding is the priority or you want the cheaper token bill.

Gemini 3.5 Flash is clearly ahead on the provisional aggregate, 88 to 83. The gap is large enough that you do not need to squint at the spreadsheet to see the difference.

Gemini 3.5 Flash's sharpest advantage is in agentic, where it averages 77.2 against 65.3. The single biggest benchmark swing on the page is Terminal-Bench 2.0, 76.2% to 63.5%. GLM-5.1 does hit back in coding, so the answer changes if that is the part of the workload you care about most.

Gemini 3.5 Flash is also the more expensive model on tokens at $1.50 input / $9.00 output per 1M tokens, versus $1.40 input / $4.40 output per 1M tokens for GLM-5.1. That is roughly 2.0x on output cost alone. Gemini 3.5 Flash gives you the larger context window at 1M, compared with 203K for GLM-5.1.

Benchmark Deep Dive

Frequently Asked Questions (4)

Which is better, Gemini 3.5 Flash or GLM-5.1?

Gemini 3.5 Flash is ahead on BenchLM's provisional leaderboard, 88 to 83. The biggest single separator in this matchup is Terminal-Bench 2.0, where the scores are 76.2% and 63.5%.

Which is better for knowledge tasks, Gemini 3.5 Flash or GLM-5.1?

Gemini 3.5 Flash has the edge for knowledge tasks in this comparison, averaging 58 versus 52.3. Inside this category, HLE is the benchmark that creates the most daylight between them.

Which is better for coding, Gemini 3.5 Flash or GLM-5.1?

GLM-5.1 has the edge for coding in this comparison, averaging 60.9 versus 54.5. Inside this category, SWE-bench Pro is the benchmark that creates the most daylight between them.

Which is better for agentic tasks, Gemini 3.5 Flash or GLM-5.1?

Gemini 3.5 Flash has the edge for agentic tasks in this comparison, averaging 77.2 versus 65.3. Inside this category, Terminal-Bench 2.0 is the benchmark that creates the most daylight between them.

Self-host vs API cost

Estimates at 50,000 req/day · 1000 tokens/req average.

Gemini 3.5 Flash
API / mo$7,875
Self-host / moN/A
Break-even
Proprietary model — self-hosting not applicable.
GLM-5.1
API / mo$4,350
Self-host / mo$18,221
Break-even264M/day
Model the full break-even

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Last updated: May 20, 2026

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